The human foot is designed so that it can rotate and pivot with regard to the lower leg, and such movements are essential to walking. One primary movement is plantar flexion, which is downward motion of the foot that occurs in the sagittal plane. In some circumstances it is necessary to limit plantar flexion to less than 90 degrees. For example, individuals with paralysis or weakness of the dorsi flexion muscle group (which lifts the foot) typically have trouble raising their foot, such as when they're walking. This dorsi flexion problem can result in tripping and falling as the front of the foot catches on obstacles. Also, individuals with excessive plantar flexion sometimes compensate when walking by lifting their foot and leg higher than normal in order to lift the front of their foot off of the ground. This unnatural lifting of the leg and foot results in a modified gait that is sometimes referred to as a steppage gait because it bears resemblance to the gait of a high-stepping horse. Walking with a steppage gait is inefficient and tiresome, and can also lead to other undesirable stresses on the body.
Various ankle-foot orthosis devices have been developed to prevent excessive plantar flexion. For example, a solid ankle brace can be placed in an individual's shoe so as to prevent flexing at the ankle joint. These braces may be improved upon by allowing a pivoting movement at the ankle joint to permit the angle between the foot and lower leg to decrease in size, while using a stop to prevent the foot from exceeding a 90 degree angle with the lower leg. These improved articulating orthosis offer significant advantages over prior rigid devices, including improved comfort, allowing a more natural walking motion by the patient, and reducing stiffness by promoting flexing of the ankle joint.
A number of companies currently make articulating orthosis and components for these orthosis, including components for the ankle joints and posterior stops. Unfortunately, many of these adjustable ankle-foot orthosis have significant shortcomings. For one, manufacture of the posterior stop is often time consuming and tedious, involving careful alignment of small components that must be delicately adjusted after installation. In addition, these posterior stops are often much larger and less attractive than desired. The problems with the large size of the stops are not limited to aesthetics, because their large size generally requires that at least part of the stop extend below the back of the shoe. Also, the stops are so large that they do not comfortably fit within a shoe, and patients frequently need two pairs of shoes of different sizes, or must modify their shoes (such as by removing part of the shoe's back or stretching the shoe to make it larger) to permit wearing of these orthosis with large posterior stops.
Therefore, a need exists for an improved ankle-foot posterior orthosis that is less cumbersome to make and use, while also being attractive, durable, and small.